Prenatal pilates / yoga - good for toning?

canerican future mom

Happy Monday ladies!!!  I hope everyone had a fabulous weekend!!

A little background...during my first trimester, I was scared to death to even move.  I've had a few m/c so I really took it easy this time.  Now that I'm out of the "danger" zone and given the clear to pick up activities, I am in desperate need to tone and tighten my areas that have been so clearly neglected (ok, they were neglected before too). 

So, I took my first ever yoga class yesterday.  I have always wanted to try yoga and I have read so many raves about it for pregnancy that I just couldn't resist anymore!!  I enjoyed it and absolutely plan to attend more sessions.  I have also signed up for a prenatal pilates class that starts in a week but it is only once a week.  I don't really feel that taking one yoga and one pilates class per week is enough...

Has anyone found that a specific type of exercise/class/video has been especially helpful in toning while pregnant?  How many days a week should I do something like yoga/pilates?